Integrated guiding device for printing ferrule or roller and ferrule or roller equipped therewith

ABSTRACT

The object of the invention is an integrated guiding device for positioning and cutting with the help of a cutting tool, a printing plate ( 16 ) on a sleeve ( 10 ) or on a printing cylinder, particularly for flexography, said sleeve or cylinder comprising an external coating ( 24 ) adapted to be deeply machined, characterized in that it comprises at least one longitudinal guide ( 30 ) along a generatrix, and/or a peripheral guide, along a circumference, provided within a matrix of material of high hardness, embedded in the thickness of said external coating. 
     The invention also comprises the sleeve or cylinder provided with this device.

BACKGROUND OF THE INVENTION

The present invention relates to a guiding device for a printing sleeveor cylinder, particularly for flexographic printing as well as thesleeves or cylinders provided with this device.

In the case of sleeves for example, it is known that they haveconsiderable advantages from a point of view of weight, when they aremade of a composite material, but there remains a problem, of attachingprinting plates to the peripheral surface of the sleeve.

Thus, the surface of the sleeves is precision ground to give it asuitable finished condition and above all such that the development,connected to the precision of the diameter, corresponds nicely to thedesired development. However, it is necessary to avoid any false roundwhich could militate against the precision of contact of the printingplate on the transfer roller or with the surface to be printed.

It is also known that printing plates must be perfectly positioned.These printing plates are thinner and thinner for evident reasons ofmaterial cost but also to improve the quality of the screen.

Because of this, as the quality increases and the length of delays inemplacing the sleeves are reduced, it is increasingly necessary toprovide suitable means for holding the printing plate on the sleeve.

In a known manner, the printing plate is connected to the sleeve withdouble-faced adhesive. Reference marks are integrated in the printingplate at the time of manufacture, which reference marks are to bebrought into coincidence with those on the sleeve.

After gluing the printing plate on the sleeve, it is necessary to cutthe double-faced adhesive which protrudes, by cutting it off as evenlyas possible. Most of the time, this cutting off is carried out manuallyby the operator, with the aid of a cutting blade, which has theimmediate consequence of leading to score lines on the external coatingof the sleeve.

When the wear is sufficiently great, it is generally necessary to sendthe sleeve to the factory to redo it, which, in addition to being a lossof time and a loss of use of the set of sleeves, is needlesslyexpensive.

Moreover, it is easy to see that the cutting-off is relatively delicatebecause any slip of the blade can lead to damage to the printing plate.

SUMMARY OF THE INVENTION

The present invention overcomes these drawbacks by means of anintegrated guiding device for mounting printing plates and for cutting.The device is very practical for the user, and permits adjustments andcuts both along generatrices and along circumferences The device is of acost altogether compatible with the price of the supports, sleeves orcylinders, whose amortization is almost immediate. The device is neutralrelative to the mechanical resistance of the sleeve with the cylinder,and is also self-compensating as to balancing and is applicable to allproducts free from surface fibers.

To this end, according to the invention, there is disclosed anintegrated guiding device for the emplacement and cutting, with the aidof a cutting tool, of a printing plate on a printing sleeve or cylinder,particularly for flexography. The sleeve or cylinder has an externalcoating adapted to be deeply machined. The guiding device has at leastone longitudinal guide, along a generatrix, and/or a peripheral guide,about a circumference, provided within a matrix of very hard material.The matrix is held within the thickness of the external coating.

According to a preferred embodiment, the matrix of very hard material isdisposed in a throat machined in the thickness of the external coating.

More particularly, the throat comprises immobilization means in thethickness of the coating, for example a dovetail profile.

The guide has a cross-section adapted to the profile of that of thecutting tool.

According to another characteristic, the matrix is made of a polymericmaterial loaded with particles of metal and/or ceramic.

The invention also relates to the sleeve or cylinder provided with thisdevice.

BRIEF DESCRIPTION OF THE DRAWINGS

The device according to the present invention will now be described inconnection with a particular embodiment, which is non-limiting, withreference to the accompanying drawings, on which the different figuresrepresent:

FIG. 1, a perspective view of a sleeve provided with a device forguiding and mounting and cutting according to the present invention,

FIG. 2, a transverse cross-sectional view of the sleeve shown in FIG. 1,and

FIGS. 3A to 3D, a sequence for production of such a sleeve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, the sleeve 10 comprises a single longitudinal groove 12, twoend peripheral grooves 14 and a medial peripheral groove 15 so as tolimit the usable size of the design.

A printing plate 16 is connected to said sleeve by, for example,double-sided adhesive. The plate 16 extends between an end peripheralgroove 14 and the medial peripheral groove 15.

The sleeve further comprises, an internal layer 18, made of fibersembodied in a resin, a layer 20 for thickness compensation, made ofcellular material, a belt 22 of high rigidity and an external coating 24of finishing resin permitting surfacing by precision grinding.

Such an arrangement of the sleeve is described in detail in patentapplication EP-A-683 040 in the name of the present assignee.

The device according to the invention is not limited to this type ofembodiment of sleeve, but more generally is applicable to all sleeves orcylinders whose external coating is free from fibers and adapted to bemachined.

The embodiment of the device is described with respect to the sequenceof FIGS. 3A to 3D. In FIG. 3A, the sleeve 10 is uncut, coming fromproduction, and is previously finely ground.

During the step of FIG. 3B, a dovetail throat 26 is machined, forexample, into the sleeve 10.

This throat 26 is of a depth less than the thickness of the externalcoating.

In an alternative embodiment, not shown, the sleeve may comprise forexample four grooves 12, equally spaced at 90° for evident reasons ofsymmetry.

Each throat 26 is then filled with a matrix 28 of a charged polymer typematerial, for example with metal or ceramic particles such that it givesa high hardness and resistance to friction. This step corresponds tothat of FIG. 3C.

So as to facilitate sliding, the present invention proposes adding tothe loaded polymer, a lubricant such as graphite and/or molybdenumbisulfide, these two examples not being considered limiting.

This matrix is for example fine ground, simultaneously with the finalfine grinding of the sleeve, after polymerization of the matrix, toavoid any projecting particles.

Each matrix 28 is then ground in its central portion to form anintegrated guide 30, whose widthwise cross-section corresponds to thatof a cutter blade and whose depth is less than the thickness of theassociated matrix 28. This machining is carried out with a diamond tool,given the hardness of the matrix of loaded polymer.

The dovetail profile gives a better integration of the associated matrixbut is not a requirement, because the polymeric matrix has an excellentbond with the other resins constituting the external coating orcladding. It suffices to select resins compatible with those of thecoating, which is within the skill of a person skilled in this art.

Other machining profiles can be envisaged for the production of thethroat with notches or crenelations, but they complicate the productionwithout giving further benefits.

Similarly, for a cylinder made of metal, for example of aluminum alloy,it can be useful to provide the device according to the inventionbecause the alloy has a hardness quite often insufficient to permitguiding a cutting tool and moreover aluminum alloys are easily marked bythe blade.

The advantage of using a polymer material is the easy emplacement in thethroat and the final surface condition, which is adapted to be finelymachined whilst offering possibilities of high hardness.

The end peripheral grooves 14 are at present used for cutting off anydouble-faced adhesive which overhangs them, when the printing plate ispositioned.

What is claimed is:
 1. An integrated guiding device for positioning aprinting plate and for use with a cutting tool, said device comprising:a sleeve having an external coating; at least one of a longitudinalnotch along a generatrix, and a peripheral notch about a circumferenceof said sleeve, the at least one notch guiding the cutting tool; said atleast one notch being in a matrix of material embedded in said externalcoating, said matrix being harder than said external coating.
 2. Thedevice according to claim 1, wherein the matrix is disposed in a throatmachined in a thickness direction of said external coating.
 3. Thedevice according to claim 2, wherein the throat has a dovetail profile.4. The device according to claim 1, wherein the notch has across-section matching a profile of the cutting tool.
 5. The deviceaccording to claim 1, wherein the matrix is a polymeric materialembedded with particles of at least one of a metal and ceramic.
 6. Thedevice according to claim 5, wherein the matrix further comprises alubricant.
 7. The device according to claim 6, wherein the lubricant isone of graphite and molybdenum bisulfide.
 8. A sleeve for supporting aprinting plate and for guiding a cutting tool, comprising: machinableexternal coating; a guiding device on said sleeve for positioning saidprinting plate, said guiding device having at least one of alongitudinal notch along a generatrix and a peripheral notch about acircumference of said sleeve; and said at least one notch guiding acutting tool.